Okay, I'm growing tired of my phone's rebooting. I've taken it apart for all the world to see
.
Okay, this is the first "layer", the board you see when you take the cover off your phone.
The serial numbers are too blurry to read, so I'll write 'em out
.
The big black chip says:
Sandisk
iNAND
SDINC2C2-2G
S92738171
CP0211027SS2 TAIWAN
Fun
, some NAND flash memory by Sandisk
.
Nothing obviously faulty here so let's move on to the next layer.
There's our next layer! The little plug in the bottom right of the picture is connected to what seems to be the antenna.
The chip on this board reads:
SAMSUNG 931
KAC0SF008N AE77
ARM G410AH 2G
N1107U11 931
ETEG45FB
Hmm, so an ARM processor?
I also love how there's a big "35" written over the chip.
This is the third layer. There are many small chips here, so I'll name just the bigger ones.
The chip in the left middle is almost shiny black while all the other chips are matte black, it reads:
NEC
MC-10103
925E3604
ARM
Another ARM processor?
And finally, the chip right above the USB port says:
M
FA972305A
PQ
Here you can see a part of what's most likely the board for the touchscreen. Not much here.
Now I noticed that to the upper left of the shiny black ARM chip on the third board, there's a small (I mean
real small, I'd estimate it 5mm in diameter and 2 mm in thickness) button cell battery.
I reckon this is a battery that performs a task similar or deadright equal to the BIOS battery in a computer.
Now a few weeks back, a friend of mine gave me an old pc that he said wasn't booting. Nothing worked. I left it gathering dust for a few weeks, thinking the power supply might be dead (it seemed to be).
It was only after a few weeks that I checked back on it, this time I tried a voltage reading on the BIOS battery, and surely it was dead. I popped in a new battery and suddenly fans started blowing! It was alive!
Well sorta...
But anyway, I haven't dared to take out the button cell in the Jet, but I've tried a direct voltage reading, which gave me roughly 1.6 volts. I know this isn't the right way to get a proper reading, but I didn't want to risk bricking the phone by taking it out before asking around. And I don't think something taking a battery will "give" me a current (and a voltage) rather than suck it.
I don't know a lot about button cells, so I did some research.
From wikipedia, I got a table. I'm having some trouble posting it directly so I'll link you.
http://en.wikipedia.org/wiki/Button_cellIt seems that all the button cells have a voltage below that of my reading, except the two that have an "end-point voltage" that is above the reading I got.
Normally I wouldn't be sure about this, but I also noticed that any changes I make in the "hidden" admin menu where CPU speed and other deeper options can be found, aren't saved for some reason.
I've changed the CPU speed a few times, but whenever I'd reboot it, the CPU speed would be set to "dynamic" again. When I scroll back and forth through the admin menu, the settings I changed stay the same, but whenever I take out the battery, put it back in and boot up the phone, everything is set back.
The settings I change in "normal" phone mode stay saved, however.
It seems to me the small button cell is (too) dead (for the phone), and the RAM isn't held.
Perhaps when the phone is on, the RAM memory is fed by the main battery, and when it is off it is fed by the button cell?
I can't make sense of the fact that the phone keeps rebooting though... Anyone?
Also the CR button cells (These are the ones with the end-point voltage at 2.0V), seem to be the most common cel button batteries found in all kinds of (Asian) devices. I suppose the reason for this is that they're cheap.
I wouldn't be surprised if the battery in the phone is of the cheap kind. It would be the perfect scenario: 999/1000 or more people would never open up their phone or give up after they did and buy a new phone or send it for repair, plus Samsung cuts the cost on the batteries. Big business!
On a final note, after some more research, I've found this on wikipedia:
"The memory and real-time clock are generally powered by a CR2032 lithium coin cell."http://en.wikipedia.org/wiki/Nonvolatile_BIOS_memoryI found this on wikpedia, and it seems to be referring mainly to PC BIOS.
"Nonvolatile BIOS memory refers to a small memory on PC motherboards that is used to store BIOS settings."It would make sense if they used the same type of button cell in phones though.
Again, my apologies for the monstrous read
. I hope this helps someone
.
